Coating material of blended pitch and tar emulsions



United States Patent 3,060,047 COATING MATERIAL 0F BLENDED PITCH AND TAR EMULSIONS Olin D. Graft and Malcolm Mitchell, Indianapolis, Ind, assignors to Reilly Tar and Chemical Corporation, Indianapolis, Ind., a corporation of Indiana N0 Drawing. Filed Apr. 6, 1960, Ser. No. 20,253 4 Claims. (Cl. 106-277) This invention relates to a discovery that, by blending together separately prepared tar-in-water and pitch-1nwater-emulsions, a coating of these blended emulsions may be applied directly to metals, such as steel, even in the absence of a primer, to obtain an outstanding protective coating. The steel does not rust under the coatlng.

The coating involving this invention may be applied to the metal in any suit-able manner as by spraying, Clipping, brushing or wiping on. The coating lends itself to normal drying at atmospheric temperatures and also to baking on the metal. A peculiarity is noted in that oily coated metal may be sprayed by or dipped in the blended emulsions and good wetting and coverage by the coating on the metal is obtained. By the term oily coated is meant that oil coating normally adhering on metals such as they come from rolling mills, but not any normally flowing oil.

As an example, one of the two emulsions entering into the blend constituting this invention, a roofing pitch emulsion, is prepared as follows:

A coal tar roofing pitch having the properties of a softening point cube in water (ASTM D61-38) of 140 to 155 F. and insoluble in carbon disulphide (ASTM 134-52) 15 to 30 percent, is melted down in a mix tank and is cut back with percent by weight of anthracene oil. To this cut back pitch in the amount of 33 to 40 percent by weight of the final emulsion, is added a filler such as talc or ball clay, within the range of from 8 to 20 percent of the final emulsion and the temperature is maintained between 105 and 115 C.

Anthracene oil may be defined (American Woo-d Preservers Association P-7-58) as a coke oven tar distillate with not more than 10 percent distilling at 235 C. and not less than 65 percent distilling at 355 C.

Water is metered into an emulsion tank in quantity of from 42 to 47.2 percent by weight of the emulsion and is heated to between 80 and 90 degrees C. Powdered or pelletized powdered bentonite of from 3.2 to 4.5 percent by weight is added to the heated water and the mixture is agitated until it is a smooth paste, free of lumps, at which time the paste temperature may be in the range of from 50 to 70 degrees C.

A'surface acting agent, a surfactant, is selected from one of the following:

Sodium isopropylnaphth'alene sulfonate (trade name Aerosol OS) Polyoxyethylene Tween 81) Sorbitan mono-oleate (trade name Span 80) Sorbitan monolaurate (trade name Span 20) Sodium salt of lignin from alkaline processes of pulping southern pine wood (trade name Indulin 'C) sorbitan mono-oleate (trade name tinued to be pumped fully into the water bentonite phase and the agitation is continued for at least an hour or longer to complete emulsification.

A second emulsion is prepared as follows:

Water in amount within the range of 38 to 44 percent by weight of the completed emulsion is brought up to a temperature of 90 degrees C.

Powdered or pelletized powdered bentoni-te in amount by weight in the range of 3.5 to 4.0 percent is stirred or agitated into the water until a smooth paste develops.

A refined coal tar is selected having a float test consistency (ASTM Dl39-49) of -220 seconds at 50 degrees C., further identified as RT-10, RT-ll, or RT-12, as outlined in specification M52-42, page 32 of part I, Standard Specifications of Highway Materials, Seventh Edition 1955, by American Association of State Highway .Ofiicials. An amount of approximately 32-38 percent of the selected tar is placed in an agitator tank at a temperature ranging from to degrees C., to which tar is first added one of the surfactants above indicated as being usable, such as the polyoxyethylene sorbitan monooleate, in the weight proportion of 0.1 to 0.3 percent, and secondly, a filler selected from powdered bentonite, ball clay, talc, slate flour, mica, or silica, in weight proportion of 8 to 14 percent.

Into the phase of water bentonite paste ranging in temperature of from 80 to '90 degrees 'C., is pumped slowly the tar-filler-surfactant phase under high agitation of the intermixture until all tar is added and completely emulsified.

The sodium salt of lignin in the amount of 0.1 to 0.3 percent by weight of the final emulsion is added by dissolving it in dilution Water. The dilution water is added in an amount varying from 5 percent to 10 percent of the final emulsion weight depending upon the consistency desired. The mixture is agitated until homogeneous.

Both emulsions, one at a time, can be made by separate feeding of the tar-filler and waterbentonite phases to a colloid mill.

Zildlllm isopropylnapthalene sulfonate are added to the end.

The two emulsions may ready to be intermixed be added together in other proportions such as 4 to 1; 2 to 1; and 1 to 1. The l to 1 ratio dipped coating under impact, when baked, is less satisfactory than the 4-1, 3-1, and 2-1 ratios, while the 1-1 ratio sprayed on coating wetted the oily metal better than the 3-1 and 4-1 ratio sprayed blends. Th 2-1 ratio ranks below the other ratios. The 3-1 ratio is the conventional blend.

Additional usable emulsions of tar are following table wherein the figures are Weight of the finished emulsion.

set out in the percentages by Water; KWK Bentonite 3. RT 10, RT 11, or RT 12 (Refined Goal Tar) 33. Tween 81 Filler Indulin C Dilution Water Additional usable emulsions of pitch are set out in a the following table wherein the figures are percentages by weight of the finished pitch emulsions:

Filler "1 Therefore it is to be seen that the discovery that two separately prepared emulsions as constituted within the ranges set forth by the foregoing examples, may be blended in the indicated proportions to give new and unexpected results as a metal coating. Coatings constituting either one alone of the tar or pitch emulsions have been employed with inferior results, but the surprise of obtaining a vastly superior coating came upon blending largely by accident the two types of the emulsions.

We claim:

1. A coating composition product comprising a blend of roofing pitch emulsion and of coal tar emulsion, Wherein the roofing pitch emulsion comprises soft pitch 33 percent to 40 percent by weight of the finished pitch emulsion; water, 42 percent to 47.2 percent, bentonite 3.2 peucent to 4.5 percent, filler 8 to 20 percent, surfactant 0.1 percent to 0.4 percent; and the coal tar emulsion comprises water 38 percent to 44 percent by final tar emulsion weight, bentonite 3.5 percent to 4.0 percent, filler 8 to 14 percent, tar 32 percent to 38 percent, and surfactants 0.1 percent to 0.3 percent each.

2. The product of claim 1 in which said pitch is cut back with percent anthracene oil.

3. The method of making a metal coating composition which comprises heating to melting point a soft coal tar roofing pitch; cutting it back with 10 percent by Weight of anthracene oil; adding a filler in the range of 8 to 20 percent to the cu't back pitch while maintaining a temperature range of from 105115 degrees C. as one phase; mixing into 42 percent to 47.2 percent of water by total emulsion weight in a temperature range of approximately from to degrees C., bentonite 3.2 to 4.5 percent of total emulsion weight and agitating until a smooth paste is formed as another phase; flowing the pitch-filler phase into said water bentonite phase and agitating to complete an emulsion; a surfactant being added to either one of said phases before flowing together; mixing together refined coal tar at a temperature range of 90 to C., from 32 to 38 percent by tar emulsion weight and a filler of from 8 to 14 percent by tar emulsion weight and a surfactant forming a tar-filler phase; mixing into Water ranging in amount from 38 to 44 percent by tar emulsion weight comminuted bentonite 3.5 to 4 percent by weight as a water bentonite phase; flowing the tar-filler phase into the water-bentonite phase ranging in temperature from 80 to 90 degrees C., and agitating until a tar emulsion is formed; and 'blending together the pitch and tar emulsions in ratios of from 1 to l to 4 to l.

4. The method of claim 3 in which the sodium salt of lignin ranging from 0.1 percent to "0.3 percent by weight in dilution water in 5 percent to 10 percent by weight, both Weights being that of the final Weight of tar emulsion, is added to the tar emulsion.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A COATING COMPOSITION PRODUCT COMPRISING A BLEND OF ROOFING PITCH EMULSION AND OF COAL TAT EMULSION, WHEREIN THE ROOFING PITCH EMULSION COMPRISES SOFT PITCH 33 PERCENT TO 40 PERCENT BY WEIGHT OF THE FINISHED PITCH EMULSION; WATER, 42 PERCENT TO 47.2 PERCENT, SURFACTANT PERCENT TO 4.5 PERCENT, FILLER 8 TO 20 PERCENT, SURFACTANT 0.1 PERCENT TO 0.4 PERCENT; AND THE COAL TAR EMULSION COMPRISES WATER 38 PERCENT TO 44 PERCENT BY FINAL TAR EMULSION WEIGHT, BENTONITE 3.5 PERCENT TO 4.0 PERCENT FILLER 8 TO 14 PERCENT, TAR 32 PERCENT TO 38 PERCENT, AND SURFACTANTS 0.1 PERCENT TO 0.3 PERCENT EACH. 